Gas-phase reactivity of sulfur-based radical ions of cysteine derivatives and small peptides

Abstract

The gas-phase reactivity of sulfur-based radical ions of cysteine derivatives and Cys-containing small peptides was studied via the use of ion-molecule reactions inside a quadrupole ion trap mass spectrometer. Both the radical cations M + and the anions (M-2H) - were generated via the gas-phase homolysis of the SNO bond of the S-nitrosylated precursors of the following: Cys, N-Ac-Cys, CysOMe, Gly-Cys, Cys-Gly, γ-Glu-Cys, γ-Glu-Cys-Gly, and Gly-Cys-Arg. The radical ions were allowed to react with the following volatile neutral reagents: allyl iodide, allyl bromide, nitric oxide, 1-propane thiol, 3-mercaptopropionic acid, dimethyl disulfide and dimethyl sulfide. The charge has little effect on..